Erosion and the siltation of waterways and dams is a real issue post fire.
To this effect the Rotary Club of Southern Mitchell, supported by the Pretty Sally Garden Club have secured loads of rice straw which are available to landholders affected by the fires. The Sunday Creek-Dry Creek Landcare Group are assisting to deliver this program, together with a Greencorp team.
Large Rice straw bales are available to property owners in fire affected areas on steep country to help with erosion and siltation control.
How does it work?
The bales are broken up into “biscuits” about 10-20cm thick. Biscuits are packed close together across slopes and drainage lines to create low barriers. These barriers take the velocity out of the water flow and restrict the movement of soil and gravel. Ring Lock and posts salvaged from the fire are placed down slope from the straw, with the netting folded back under to help hold the straw in place.
Photo, Rice straw sediment traps, Walls Crossing
On slopes, follow the contours to avoid channelling the water (fallen branches and small trees can also be placed across slopes to slow water).
In drainage lines, ensure that the lowest point in the barrier is in the middle so that water spills over the barrier rather than going around the side and creating a new line of erosion. Several barriers can be placed in series down a drainage line. Solid structures like stumps and old machinery are not recommended in drainage lines – water will bypass them and create more erosion (and they may cause pollution of water).
The ash and soil that builds up behind the straw can be later used as a planting bed.
The bales could also be broken up and spread across an area to introduce much needed cover from heavy rain and build up biomass on the soil. However, the straw needs to be thinly spread - if the straw is too thick, it may prevent plants from growing.
Why Rice Straw?
Rice straw does not harbour pasture weeds and holds together as a mat, hence it does not blow away in the wind. The rice straw will take approximately 1 year to decompose and generally animals do not find it palatable.
How large are the Bales?
The Bales measure 8*4*4 and a trailer or ute is need for transportation.
Demonstration sites and trials
A demonstration site has been established at Walls Crossing, Clonbinane, this was undertaken in partnership with Greencorp and Mitchell Shire Council. Rice straw, fallen branches and ring lock fencing recovered from fences damaged by the fires have been strategically placed to slow down and spread out water flow from rainfall, preventing further ash and sediments to entering the Sunday Creek. Council will develop an educational sign to raise awareness of the project. The project looks to improve environmental outcomes and act as an educational demonstration site for erosion control on fire affected creek lines and gullies.
Trials using the rice straw have also been established in San Mateo Court, where the results are very promising.
A demonstration day titled “Managing erosion after fire” held on the 15th August, was well attended, with most participants also using the opportunity to load and deliver rice straw bales to their properties
Further advice
Department of Primary Industries staff are available for technical advice and may be able to assist with funding for fencing and revegetation and more complex engineering works at erosion sites. Contact the Broadford Office on 5782 0600
How do I go about being part of this project?
Before receiving the bales, the organisers seek a verbal commitment form landholders to undertake the work properly and ensure that they have an understanding of the process. It is also beneficial if recipients join the Landcare group as an indication of their ongoing commitment to good land management.